Lock miter joint



. July 8, 1930.

J. 5. BURTON LOCK HITER JOINT Filed Dec. 30, 1929 Patented July 8, 1 930 JOHN S. BURTOF', OF GLENS FALLS, NEW YORK LOCK I /ZITER JOINT Application filed December 30, 1929. Serial No. 417,534.

The invention has relation to miter joints, having for an object to provide a lock joint of this description, designed particularly for interior door and window trim, wherein the use of glue or clamps are not required and avoiding the possibility of the joint opening or pulling apart.

The invention consists in the novel construction and combinations of parts as set forth in the appended claims.

in the accompanying drawings illustrating the invention, Figure 1 is a side view partly in section, of a corner of window or door trim, showing the joint before being driven home; Figure 2 is a similar view showing the joint as driven home; Figure 3 is a similar view on a larger scale of a part of the joint; Figure 4 is a plan view of one member of the oint, showing the recess; and Figure 5 is a similar view showing in dotted lines the portion of the recess out out by the screw head.

In these drawings, the numeral 1 designates one part of the trim, such as the top part, and 2 the other or side part or member, mitered at 3. The part or member 1 at the miter, is provided with two spaced screws a, 4, screwed therein to leave the head and part of the adjacent shank thereof exposed as at 5.

The part- 2 of the trim at the miter, is provided with two spaced key-hole shaped recesses 6, 6, at right angles to the miter edge, as are also said screws.

In making the oint, the two parts or members of the trim are fitted together with the heads of the screws engaging the circular end parts of the recesses 6, 6, as shown in Figure 1, there being a slight space 7 between the two members or parts of the trim at the miter.

The joint is now driven home to bring the heads of the screws at the other or opposite ends of the key hole shaped slots, said heads cutting their way through the wood as they go, and owing to the fact that the grain of the wood shown at 8 is presented angularly at an angle of about forty-five degrees to the sharp steel screw heads, said heads as they are driven home will tend to open the grain of the wood in wedge fashion and to thereby draw the two parts of the trim together, owing to the screw heads constantly seeking to enter farther into the grain of the wood, this being on the principle that passages 9 in the grain of the wood are being constantly presented to the sharp edge of the screw head as it cuts its way home, and wherein said screw head seeks or tends to enter to thereby pull the parts of the joint together as stated.

One of the screws, and related slots or recesses of key-hole shape is provided near the short corner of the miter, thereby avoiding any possibility of the joint opening or pulling apart as one part pulls against the other.

I claim 1. A miter joint for interior door and window trim and the like, wherein the grain of the wood of one member of the joint runs longitudinally of said member; the latter being provided at its miter edge with a keyhole shaped recess at right angles to said miter edge and at an angle with respect to said grain of the wood, the other member of the joint being provided at its miter edge with a screw the head and adjacent part of the shank of which is exposed and engaged with the circular partof the key-hole shaped recess and driven home to out its way through the wood, the grain of which presents itself angularly to the advancing head of the screw to draw the two members of the joint together in wedge fashion.

2. A miter oint for interior door and win dow trim and the like, wherein the grain of the wood of one member of the joint runs longitudinally of said member; the latter being provided with a key-hole shaped recess at its miter edge and at an angle with respect to said grain of the wood and at right angles to said miter edge, the other member of the joint being provided at its miter edge with a screw the head and adjacent shank of which is exposed and engaged with said keyhole shaped recess and with the grain of the wood in wedge fashion to draw the two members of the joint together.

A miter joint for interior door and window trim and the like, wherein the grain of thbwobd bfonfmmhe'i' of the jo intfriins longitudinally of said 'x nemberg the latter j being,providedwith' two key hole shap ed r eclasses at; righbangles to, its miter 'dgeand fianangl lwfth' sp M "said gm" f h twomjembers of ain toso "irict'ionally hpldithms one if 1the-sctewsland- 1'Q md 3 06 ei g lOGflf6d-I i3arth ShOI W I I 15 corner of the miter to avoidtendncy of open I i of the joint. I v l' n testimony whereof Iafiix my signature.

I J OHN S; BURTON. 

